Cpanel setup behind firewall not working

I setup my server behind a firewall and gave the server an ip of 192.168.1.99. It has a public ip and I forwarded the ports to the private ip.

what is the correct way to set the server up for this to work with cpanel/whm? I added the public ip address to the pool so that the public ip is now assigned to the site. When I goto the website I get the default everything was setup ok, however there are files in the public_html dir.

Any ideas? Is there something I can follow to get this working correctly?